The invention relates to a method and an arrangement for producing compound filters for products in the tobacco-processing industry. An arrangement of the character to which the present invention relates includes a filter tube feeding element and at least one conveying element, into which the filter tubes are inserted and which supply or supplies these filter tubes to at least one processing station. The invention furthermore relates to the use of pre-manufactured filter tubes for producing compound filters for products in the tobacco-processing industry, a corresponding filter tube for producing compound filters for products in the tobacco-processing industry, as well as a compound filter-manufacturing system for the products, which system comprises a filter tube feeding device and a conveying system for conveying the filter tubes along a predetermined movement path.
Published German Patent Application No. 17 82 364, owned by the assignee of the present application, discloses a method and arrangement for producing compound filters, and in particular describes an arrangement, commercially known as the “Bernhard” machine and distributed by the present assignee, for producing filters containing filter granules. Published German Patent Application No. 17 82 364 corresponds to British Patent No. 1.243.977 and to U.S. Pat. No. 3,603,058 granted on Sep. 7, 1971 to Bernhard Schubert for “Method and Apparatus for the Production of Composite Filter Tips.” Compound filters, also referred to as multi-segment filters, produced by the “Bernhard” machine consist of at least two and typically up to eight filter elements, arranged in an optional sequence. Different filter elements or segments are arranged inside a casing or sleeve in the shape of a tube. The filter elements can include soft filter elements such as cellulose acetate, paper, fleece, or relatively hard filter elements such as granules, sintered elements, hollow-cylinders or hollow-chambers and capsules and the like. It is not necessary for the respective filtering materials to consist 100% of a single type of material. For example, the filtering material can comprise mixed materials such as granules in a cellulose acetate and can include granulated materials such as active charcoal. The properties of compound filters can vary extremely, depending on the materials used and the filter-segment sequence. These filters are preferably attached to the end of rod-shaped tobacco articles such as cigarettes, cigars, cigarillos, and analogous rod-shaped smokers'products.
The granulate-filling machine described in U.S. Pat. No. 3,603,058 to Schubert produces filters containing granulate, and in particular triple filters. A triple filter is understood to be a filter consisting of three filter segments. The above mentioned Bernhard filling machine produces a triple filter of twice unit length. For cigarette production, the filter is arranged between two long, tobacco-containing articles wrapped in cigarette paper and is then cut in the center to obtain two cigarettes provided with a filter. U.S. Pat. No. 3,603,058 to Schubert discloses a continuously circulating conveyor with receptacles for the filter tubes for conveying the filter tubes cross-axially. During the cross-axial conveying, filter plugs cut from a longer filter rod and granulate are alternately inserted into the tube. The filter plugs are pushed into the tube with the aid of a transfer mechanism in the form of a plunger or push rod while the granulated material drops into the tube under the effect of gravity.
The relatively numerous steps required for operating the “Bernhard” machine, in particular the necessity for relatively far-reaching movements, limit the output of the granulate-filling machine described in U.S. Pat. No. 3,603,058 to Schubert. Given the increasingly higher output of cigarette-production machines, there is a need to accelerate the production of corresponding filters as well.